When opening a file with AutoCAD20 10, double-click the file to pop up the "Signature Confirmation Options" dialog box, and click OK to confirm that the CAD20 10 software is not running and the file is not opened. Two solutions:

1. Right-click the drawing you want to print, click Open Mode, click Select Program, and then select autocad dwg launcher. After typing the following program that always uses this option, click OK.

2. You can also try Tools-Options-Open and Save-Security Options-Digital Signature, and then click OK.